6442721 has 2 divisors, whose sum is σ = 6442722. Its totient is φ = 6442720.

The previous prime is 6442703. The next prime is 6442763. The reversal of 6442721 is 1272446.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 6250000 + 192721 = 2500^2 + 439^2 .

It is a cyclic number.

It is not a de Polignac number, because 6442721 - 2¹⁰ = 6441697 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (6442771) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3221360 + 3221361.

It is an arithmetic number, because the mean of its divisors is an integer number (3221361).

Almost surely, 2^6442721 is an apocalyptic number.

It is an amenable number.

6442721 is a deficient number, since it is larger than the sum of its proper divisors (1).

6442721 is an equidigital number, since it uses as much as digits as its factorization.

6442721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2688, while the sum is 26.

The square root of 6442721 is about 2538.2515635768. The cubic root of 6442721 is about 186.0757486207.

The spelling of 6442721 in words is "six million, four hundred forty-two thousand, seven hundred twenty-one".